By using horizontal method,

We have;

= (x² + xy + y²) × (x - y)

= x(x² + xy + y²) - y(x² + xy + y²)

= x³ + x²y + xy² - x²y – xy² - y³

By arranging the expression in the form of descending powers of x,

We get;

= (x³ - y³)